An analysis of the mechanical behavior of Al-Al3Ni composites

Commercial purity Al-Al₃Ni eutectic composites have been prepared by directional solidification at growth rates ranging from 9.63 x 10^-3 to 1.0 mm/s. The composites were tested in tension and in compression and the results were analyzed using a simple model taking into consideration the difference in Poisson’s ratio of the phases, interfiber spacing, and discontinuity and premature fracture of fibers. The theoretically predicted values of the tangent modulus and strength in tension and compression were shown to closely fit the experimental results up to a growth rate of about 0.3 mm/s. Beyond this value, the excessive misalignment of the fibers caused some deterioration in the mechanical properties and a change in the mode of fracture. It has been concluded that the elastic constrained matrix exerts considerable effect on the mechanical properties thus providing an effective means of improving them by increasing the surface area of the fiber-matrix interface.